中文摘要：

基于镇扬江段河势变化剧烈、感潮特性明显、水沙运动复杂的特征,建立了二维非稳态水流、水质及泥沙耦合数学模型,在有限体积法框架下应用通量差分裂（FDS）格式计算模型中各跨单元边界的数值通量,基于实测数据对模型进行了率定验证.运用所建模型对洪季、枯季镇扬江段水沙过程进行数值仿真,结果表明：（1）镇扬江段汛期流速约为0.72—1.98m/s,枯水期流速约为0.33—1.24m/s,汛期平均流速约比枯水期增加了40.6%;（2）汛期水动力条件较好,沿河排污口最大污染带长度约1550m,枯水期总污染带长度约2800m,比汛期增加了46.2%;（3）汛期镇扬江段平均含沙量为0.12—0.20kg/m3,枯水期平均含沙量为0.07—0.11kg/m3,汛期含沙量较枯水期增加了40%;汛期,泥沙浓度从上游至下游沿河长方向基本呈现递减趋势;枯水期,由于径流、潮流双重作用明显,泥沙浓度沿程变化较小.

英文摘要：

Due to the poignant changes of watercourse, obvious tide-induced impacts and complex transport principles of water-sediment, a 2-D unsteady coupling numerical model of water current, water quality and sediment for the Zhenjiang-Yangzhou section of the Yangtze River was established. The flux difference splitting （FDS） scheme was employed to calculate the numerical flux across the interface between cells in the framework of the finite volume method. Parameters of the model were calibrated and validated against the field measured data. The process of water-sediment in flood seasons and dry seasons were simulated by the model. The results indicate that： （ 1 ） the average velocity in dry seasons in Zheng-Yang section ranges from 0. 33 to 1.24m/s, and that in flood seasons ranges from 0. 72 to 1.98m/s, which is increased by 40. 6% approximately ; （ 2 ） the length of the maximum pollution belt in flood season is 1550m, and it is less than that in the dry season, because of the better hydraulic condition; （3） the average sediment concentration in flood seasons and dry seasons range respectively from 0. 12 to 0. 20kg/m^3 and 0. 07 to 0. 11kg/m^3. During the flood seasons, the sediment concentration is gradually decreased in the watercourse direction, however, the concentration in dry seasons doesn＇ t vary evidently because of the double impacts induced by runoff and tide.